This article was downloaded by: [Carnegie Mellon University] On: 14 January 2015, At: 00:18 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Ergonomics Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/terg20
Preparation of dynamic posture and occurrence of low back pain a
KOJI OMINO & YOSHIO HAYASHI
a
a
Department of Administration , Faculty of Science and Technology, Keio University , 3-14-1 Hiyoshi, Yokohama, Japan Published online: 31 May 2007.
To cite this article: KOJI OMINO & YOSHIO HAYASHI (1992) Preparation of dynamic posture and occurrence of low back pain, Ergonomics, 35:5-6, 693-707, DOI: 10.1080/00140139208967847 To link to this article: http://dx.doi.org/10.1080/00140139208967847
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
ERGONOMICS,
1992. YOLo 35. NOS 5/6. 693-707
Preparation of dynamic posture and occurrence of low back pain KOJi OMINO
and Y OSHIO HAYASHI
Department of Administration, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Japan
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
Keywords: Low back pain; Posture; Preparatory set.
Improper posture is considered as one of the causes for low back pain. This study focused attention on low back pain that occurs when people adopt a dynamic posture. Low back pain in attendants was investigated as a typical example oflow back pain in a dynamic posture. When multi-dimensional quantification III was applied 10 the results of the investigation, low back pain was found to occur in six postural patterns: bending knee posture, the posture of lifting and holding a light object, the posture of tilting the trunk, working posture to push a cart, the posture of turning or lifting a cart, and the posture of stretching. This survey found that low back pain frequently occurred when an unexpected load was imposed on the lumbar region and experiments were conducted to simulate the unexpected loading of this region. The experimental results showed that lumbar muscular activity was not fast enough to cope with the load and resulted in an increased swaying of the trunk. This swaying was considered to induce a load on the lumbar region. It is concluded that low back pain can be prevented if an appropriate preparatory set is taken.
I. Introduction Many studies have attributed occupational low back pain to work posture. Howorth (1946) classified working posture into static posture and dynamic posture. Low back pain resulting from the former is considered to be different in nature from low back pain resulting from the latter. In static posture, low back pain can occur when the lumbar region is constantly loaded for long time. In the case of dynamic posture, Jow back pain can occur when the lumbar region is loaded for a shon time or repeatedly subjected to such loading. Low back pain arising from dynamic posture is analysed here. Howorth (1946) defined dynamic posture as a posture in motion, in action or in preparation for action. He called the posture in preparation for action the basic dynamic posture and cited it as one of the factors that have a great effect on movement. In fact, cases have been observed in which attendants suffer from low back pain when they are unable to adopt the basic dynamic posture due to the unexpected rocking of their vehicle. This study investigated what dynamic posture induced low back pain and what effect the preparatory set for the dynamic posture had on the lumbar region. The actual analysis addressed the workplace where attendants must frequently adopt dynamic postures. The postural patterns of the attendants who suffered from low back pain were indicated by statistical methods. Considering that the attendants could prevent low back pain by adopting a suitable basic dynamic posture from among the postural patterns, the importance of preparation was emphasized. Experiments were conducted to simulate low back pain due to an unexpected loading of the lumbar region and to measure the loading of this region. 00 14-0 139/92 $3·00 C 1992 Taylor & Francis Ltd.
694
K. Omino and Y. Hayashi
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
2.
Posture adopted by attendants when they suffered from low back pain
2.1. Methods Occurrences of low back pain among attendants were investigated using survey items developed by the authors. The attendants mainly serve drinks and meals to passengers. They often adopt dynamic postures to provide the services and mostly sufTer from low back pain in these dynamic postures. Cluster analysis was performed on all categories of survey items. Highly correlated categories were classified into groups. These groups were considered as assemblies of specific low back pain-related categories and were regarded as representing low back pain patterns of the attendants. Multi-dimensional quantification III was used as the cluster analysis method applicable to nominal scale data. This study focused attention on finding what posture induced low back pain in the attendants. Cluster analysis was performed on categories of posture-related items, and postural patterns in which low back pain occurred were found. This technique was applied to other items in stages, and categories classified accordingly were added to the postural patterns concerned. The conditions in which the attendants adopted the posture and suffered from low back pain were analysed by the following procedure: (1) Thirty-three survey items were subjectively divided into groups by posture, work task, work object, and work environment, among other factors. (2) Attention was focused on the posture item group as it was most closely related to the occurrence of low back pain among the item groups. Multi-dimensional quantification III was applied to the posture item group. The categories were classified into several groups as a result. The groups were interpreted as postural patterns that induced low back pain and were called the basic groups. (3) Multi-dimensional Quantification III was applied to the combination of the posture item group with another item group; for example, work task item group. If the basic groups were still identifiable, the work task group categories were assigened to the nearest group on a scatter diagram. The relationship between the two item groups conferred an additional meaning on to the basic groups. Multi-dimensional quantification III was similarly applied to the combinations of the posture item group with the work object item group, work environment item group, and so on. (4) These interpretations of the basic groups were summarized to obtain an overall picture.
An example in which the above procedure was applied to the low back pain reports of attendants is described below.
2.2. Results A data matrix was prepared from 98 reports of low back pain from attendants according to the items described above and was statistically processed as described below. 2.2.1. Ten item groups: The 33 items were divided into ten items groups as shown in table I. The seven items in the first posture item group comprise the basic groups mentioned above.
Dynamic posture and low back pain Table I. Items
Posture
Lumbar region; Arm; Leg I; Leg 2; Object of attention 1; Object of attention 2; Twist of lumbar region Work task Work object I; Work object 2; Force application or not; Horizontal force; Vertical force Obstacle; Resistance; Footstep Job classification; Place; Vehicle type History; Symptom; Sleep Statue; Weight Year employed Number of days required for recovery
Health
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
Ten item groups.
Item group
Work task Work object and force application Poor condition Work environment Physique Experience Severity of injury
695
2.2.2. Pattern classification by posture: Multi-dimensional quantification III was applied to the seven items of data related to the posture of attendants when they suffered from low back pain. Three characteristic axes with high contributions were taken into account, and the category variables corresponding to axes I to 3 were plotted on a three-dimensional scatter diagram to visually illustrate the data structure. The category variables were divided into six groups. Since the items used here are related to posture, the six groups indicate the postural characteristics of the attendants when they suffered from low back pain. Figure I is a two-dimensional scatter diagram with axes I and 2 taken as the vertical and horizontal axes, respectively. The contribution of each axis is plotted on the axis. Categories considered to comprise a group are enclosed in a circle and are summarized in table 2. 8xls 1
~rr~
~
one leo
~ld
anll flex
~
Leg: Press
6th Basic group
Left
4th Basic group
Figure I.
Postural patterns associated with occurrence of low back pain.
696
K. Omino and Y. Hayashi Table 2.
Basic group
Lumbar region
Postural patterns associated with occurrence of low back pain. Arm
I
2
3 4 5
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
6
Leg
Direction of attention
Bent Lift; Hold; Not used Hold and extend Push Pull and turn Hold and flex; Extend; Support body
Diagonally downward Forward walk Backward walk
Forward Forward
On one leg
Diagonally upward
Group 1 is characterized by the posture in which the attendant bends the legs and has a low centre of gravity. It is related to the lifting and holding of the arms and the diagonally downward direction of attention. Group 2 is characterized by the forward "tilting posture of the trunk and is related to the holding of the arms and the diagonally downward direction of attention. Group 3 is characterized by the posture in which the attendant extends and holds the arms straight and bends the trunk forward. It is related slightly to the extending of the legs and strongly to the diagonally downward direction of attention. Group 4 is characterized by the standing posture in which the attendant walks forward. It is related to the pushing or pulling of the arms as well as to the fore-and-aft direction of attention. Group 5 is characterized by the posture in which the attendant walks backward with the waist pushed backward as well as by the rotating and pulling of the arms. Group 6 is characterized by the posture in which the attendant stands tiptoe on one leg. It is related slightly to "the holding or bending ofthe arms and the supporting of the trunk and strongly to the diagonally upward direction of attention. The characteristics of the respective groups tended to appear in the extending or bending of the arms and legs and the upward or downward direction of attention on the whole, as discussed above. There are some categories that did not belong to any groups. The position of the legs (shown on the left in figure I) seems to be related to both groups I and 2. The left direction of attention and the right direction of attention are taken to be related to groups 1 and 4, respectively. The twisting of the waist and the use of one or both legs are related to none of the six groups.
2.2.3. Relationship of basic groups with other item groups: Multi-dimensional Quantification III was applied to the combination of the posture item group with the work task item group in order to see the relationship between the work task item group and the basic groups obtained as described above. The results are shown in figure 2. Task categories nearest to a basic group are included in the basic group.Task categories related to the basic groups are summarized in table 3. Work tasks closely related to groups 1 and 2 suggest that these two groups are characteristic in that the occurrence of low back pain is not appreciably attributable to the servicing of passengers.
Dynamic posture and low back pain
697
ax1.ll 1
6th Basic group
Itlusekeep lng", galley Doing wcel1aneous tasks
4th Basic group
eY ~
Taki~tlf"f1if boarding task 2nd Basic group ))leeklng Joalts on board lnsptfUng safety oevl~ 1nk
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
--Jiervin Ilea Is
5th Basic group
i~rD~ cdln~--1st
serving
3rd~~ r~g
Basic
group
'9
~
aoerlt1f
.9+
~
selling
Basic group
Ergonomics Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/terg20
Preparation of dynamic posture and occurrence of low back pain a
KOJI OMINO & YOSHIO HAYASHI
a
a
Department of Administration , Faculty of Science and Technology, Keio University , 3-14-1 Hiyoshi, Yokohama, Japan Published online: 31 May 2007.
To cite this article: KOJI OMINO & YOSHIO HAYASHI (1992) Preparation of dynamic posture and occurrence of low back pain, Ergonomics, 35:5-6, 693-707, DOI: 10.1080/00140139208967847 To link to this article: http://dx.doi.org/10.1080/00140139208967847
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
ERGONOMICS,
1992. YOLo 35. NOS 5/6. 693-707
Preparation of dynamic posture and occurrence of low back pain KOJi OMINO
and Y OSHIO HAYASHI
Department of Administration, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama, Japan
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
Keywords: Low back pain; Posture; Preparatory set.
Improper posture is considered as one of the causes for low back pain. This study focused attention on low back pain that occurs when people adopt a dynamic posture. Low back pain in attendants was investigated as a typical example oflow back pain in a dynamic posture. When multi-dimensional quantification III was applied 10 the results of the investigation, low back pain was found to occur in six postural patterns: bending knee posture, the posture of lifting and holding a light object, the posture of tilting the trunk, working posture to push a cart, the posture of turning or lifting a cart, and the posture of stretching. This survey found that low back pain frequently occurred when an unexpected load was imposed on the lumbar region and experiments were conducted to simulate the unexpected loading of this region. The experimental results showed that lumbar muscular activity was not fast enough to cope with the load and resulted in an increased swaying of the trunk. This swaying was considered to induce a load on the lumbar region. It is concluded that low back pain can be prevented if an appropriate preparatory set is taken.
I. Introduction Many studies have attributed occupational low back pain to work posture. Howorth (1946) classified working posture into static posture and dynamic posture. Low back pain resulting from the former is considered to be different in nature from low back pain resulting from the latter. In static posture, low back pain can occur when the lumbar region is constantly loaded for long time. In the case of dynamic posture, Jow back pain can occur when the lumbar region is loaded for a shon time or repeatedly subjected to such loading. Low back pain arising from dynamic posture is analysed here. Howorth (1946) defined dynamic posture as a posture in motion, in action or in preparation for action. He called the posture in preparation for action the basic dynamic posture and cited it as one of the factors that have a great effect on movement. In fact, cases have been observed in which attendants suffer from low back pain when they are unable to adopt the basic dynamic posture due to the unexpected rocking of their vehicle. This study investigated what dynamic posture induced low back pain and what effect the preparatory set for the dynamic posture had on the lumbar region. The actual analysis addressed the workplace where attendants must frequently adopt dynamic postures. The postural patterns of the attendants who suffered from low back pain were indicated by statistical methods. Considering that the attendants could prevent low back pain by adopting a suitable basic dynamic posture from among the postural patterns, the importance of preparation was emphasized. Experiments were conducted to simulate low back pain due to an unexpected loading of the lumbar region and to measure the loading of this region. 00 14-0 139/92 $3·00 C 1992 Taylor & Francis Ltd.
694
K. Omino and Y. Hayashi
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
2.
Posture adopted by attendants when they suffered from low back pain
2.1. Methods Occurrences of low back pain among attendants were investigated using survey items developed by the authors. The attendants mainly serve drinks and meals to passengers. They often adopt dynamic postures to provide the services and mostly sufTer from low back pain in these dynamic postures. Cluster analysis was performed on all categories of survey items. Highly correlated categories were classified into groups. These groups were considered as assemblies of specific low back pain-related categories and were regarded as representing low back pain patterns of the attendants. Multi-dimensional quantification III was used as the cluster analysis method applicable to nominal scale data. This study focused attention on finding what posture induced low back pain in the attendants. Cluster analysis was performed on categories of posture-related items, and postural patterns in which low back pain occurred were found. This technique was applied to other items in stages, and categories classified accordingly were added to the postural patterns concerned. The conditions in which the attendants adopted the posture and suffered from low back pain were analysed by the following procedure: (1) Thirty-three survey items were subjectively divided into groups by posture, work task, work object, and work environment, among other factors. (2) Attention was focused on the posture item group as it was most closely related to the occurrence of low back pain among the item groups. Multi-dimensional quantification III was applied to the posture item group. The categories were classified into several groups as a result. The groups were interpreted as postural patterns that induced low back pain and were called the basic groups. (3) Multi-dimensional Quantification III was applied to the combination of the posture item group with another item group; for example, work task item group. If the basic groups were still identifiable, the work task group categories were assigened to the nearest group on a scatter diagram. The relationship between the two item groups conferred an additional meaning on to the basic groups. Multi-dimensional quantification III was similarly applied to the combinations of the posture item group with the work object item group, work environment item group, and so on. (4) These interpretations of the basic groups were summarized to obtain an overall picture.
An example in which the above procedure was applied to the low back pain reports of attendants is described below.
2.2. Results A data matrix was prepared from 98 reports of low back pain from attendants according to the items described above and was statistically processed as described below. 2.2.1. Ten item groups: The 33 items were divided into ten items groups as shown in table I. The seven items in the first posture item group comprise the basic groups mentioned above.
Dynamic posture and low back pain Table I. Items
Posture
Lumbar region; Arm; Leg I; Leg 2; Object of attention 1; Object of attention 2; Twist of lumbar region Work task Work object I; Work object 2; Force application or not; Horizontal force; Vertical force Obstacle; Resistance; Footstep Job classification; Place; Vehicle type History; Symptom; Sleep Statue; Weight Year employed Number of days required for recovery
Health
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
Ten item groups.
Item group
Work task Work object and force application Poor condition Work environment Physique Experience Severity of injury
695
2.2.2. Pattern classification by posture: Multi-dimensional quantification III was applied to the seven items of data related to the posture of attendants when they suffered from low back pain. Three characteristic axes with high contributions were taken into account, and the category variables corresponding to axes I to 3 were plotted on a three-dimensional scatter diagram to visually illustrate the data structure. The category variables were divided into six groups. Since the items used here are related to posture, the six groups indicate the postural characteristics of the attendants when they suffered from low back pain. Figure I is a two-dimensional scatter diagram with axes I and 2 taken as the vertical and horizontal axes, respectively. The contribution of each axis is plotted on the axis. Categories considered to comprise a group are enclosed in a circle and are summarized in table 2. 8xls 1
~rr~
~
one leo
~ld
anll flex
~
Leg: Press
6th Basic group
Left
4th Basic group
Figure I.
Postural patterns associated with occurrence of low back pain.
696
K. Omino and Y. Hayashi Table 2.
Basic group
Lumbar region
Postural patterns associated with occurrence of low back pain. Arm
I
2
3 4 5
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
6
Leg
Direction of attention
Bent Lift; Hold; Not used Hold and extend Push Pull and turn Hold and flex; Extend; Support body
Diagonally downward Forward walk Backward walk
Forward Forward
On one leg
Diagonally upward
Group 1 is characterized by the posture in which the attendant bends the legs and has a low centre of gravity. It is related to the lifting and holding of the arms and the diagonally downward direction of attention. Group 2 is characterized by the forward "tilting posture of the trunk and is related to the holding of the arms and the diagonally downward direction of attention. Group 3 is characterized by the posture in which the attendant extends and holds the arms straight and bends the trunk forward. It is related slightly to the extending of the legs and strongly to the diagonally downward direction of attention. Group 4 is characterized by the standing posture in which the attendant walks forward. It is related to the pushing or pulling of the arms as well as to the fore-and-aft direction of attention. Group 5 is characterized by the posture in which the attendant walks backward with the waist pushed backward as well as by the rotating and pulling of the arms. Group 6 is characterized by the posture in which the attendant stands tiptoe on one leg. It is related slightly to "the holding or bending ofthe arms and the supporting of the trunk and strongly to the diagonally upward direction of attention. The characteristics of the respective groups tended to appear in the extending or bending of the arms and legs and the upward or downward direction of attention on the whole, as discussed above. There are some categories that did not belong to any groups. The position of the legs (shown on the left in figure I) seems to be related to both groups I and 2. The left direction of attention and the right direction of attention are taken to be related to groups 1 and 4, respectively. The twisting of the waist and the use of one or both legs are related to none of the six groups.
2.2.3. Relationship of basic groups with other item groups: Multi-dimensional Quantification III was applied to the combination of the posture item group with the work task item group in order to see the relationship between the work task item group and the basic groups obtained as described above. The results are shown in figure 2. Task categories nearest to a basic group are included in the basic group.Task categories related to the basic groups are summarized in table 3. Work tasks closely related to groups 1 and 2 suggest that these two groups are characteristic in that the occurrence of low back pain is not appreciably attributable to the servicing of passengers.
Dynamic posture and low back pain
697
ax1.ll 1
6th Basic group
Itlusekeep lng", galley Doing wcel1aneous tasks
4th Basic group
eY ~
Taki~tlf"f1if boarding task 2nd Basic group ))leeklng Joalts on board lnsptfUng safety oevl~ 1nk
Downloaded by [Carnegie Mellon University] at 00:18 14 January 2015
--Jiervin Ilea Is
5th Basic group
i~rD~ cdln~--1st
serving
3rd~~ r~g
Basic
group
'9
~
aoerlt1f
.9+
~
selling
Basic group
